Noise Reduction

Inactive Publication Date: 2009-10-08
QUALCOMM TECH INT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]It would therefore be valuable to have an impro

Problems solved by technology

Unfortunately, obtaining reliable estimates of these has shown to be extremely difficult in the past due to the high complexity of various noisy environments.
Many algorithms perform well in one situation but fail in other situations.
Since the nature of the environment is not normally known in advance, and may change as a user moves from place to place, many algorithms provide inconsistent and unsatisfactory results.

Method used

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Examples

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Embodiment Construction

[0017]The system described below estimates noise in an audio signal by means of an adaptive system having cascaded controller blocks.

[0018]This example will be described in the context of a device for estimating noise in a source audio signal. FIG. 2 shows the general logical architecture that will be employed. The source audio signal d(n) will be applied to an analysis filter bank (AFB) 10 analogous to that shown in FIG. 1 and to a harmonicity estimation unit 11 which generates an output dependent on the estimated harmonicity of the source signal. The outputs of the analysis filter bank 10 and the harmonicity estimation unit 11 are provided to a statistical analysis unit 12 which generates minimum statistics information. The statistical analysis unit processes the output of the AFB in a manner that is dependent on the output of the harmonicity estimation unit. The outputs of the analysis filter bank 10 and the statistical analysis unit are applied to an adaptive noise estimation un...

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Abstract

A signal processor for estimating noise power in an audio signal includes a filter unit for generating a series of power values, each power value representing the power in the audio signal at a respective one of a plurality of frequency bands; a signal classification unit for analysing successive portions of the audio signal to assess whether each portion contains features characteristic of speech, and for classifying each portion in dependence on that analysis; a correction unit for estimating a minimum power value in a time-limited part of the audio signal, estimating the total noise power in that part of the audio signal and forming a correction factor dependent on the ratio of the minimum power value to the estimated total noise power, the correction unit being configured to estimate the minimum power value and the total noise power over only those portions of the time-limited part of the signal that are classified by the signal classification unit as being less characteristic of speech; and a noise estimation unit for estimating noise in the audio signal in dependence on the power values output by the filter unit and the correction factor formed by the correction unit.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to estimating features of a signal, particularly for the purpose of reducing noise in the signal. The features could be noise power and gain. The signal could be an audio signal.[0002]There are many types of devices that detect and process speech signals. Examples include headsets and mobile phones. In those devices it is often desired to reduce the noise in the detected signal in order to more accurately represent the speech component of the signal. For instance, in a mobile phone or a headset any audio that is detected by a microphone may include a component representing a user's speech and a component arising from ambient noise. If that noise can be removed from the detected signal then the signal can sound better when it is played out, and it might also be possible to compress the signal more accurately or more efficiently. To achieve this, the noise component of the detected audio signal must be separated from the voice co...

Claims

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Application Information

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IPC IPC(8): G10L21/02
CPCG10L21/0208G10L2021/02163G10L25/90G10L25/78
InventorSUN, XUEJINGYEN, KUAN-CHIEHALVES, ROGERIO GUEDES
OwnerQUALCOMM TECH INT